//1576.替换所有的问号
class Solution {
    public String modifyString(String ss) {
        char[] s = ss.toCharArray();
        int n = s.length;
        for(int i = 0;i < n;i++){
            //替换
            if(s[i] == '?'){
                for(char ch = 'a';ch <= 'z';ch++){
                    if((i == 0 || ch != s[i-1]) && (i == n - 1 || ch != s[i + 1])){
                        s[i] = ch;
                        break;
                    }
                }
            }

        }
        return String.valueOf(s);
    }
}